simplemerge: avoid quadratic concatenation when building output text I haven't checked if the difference is measurable, but the new version is no less readable or idiomatic, so I don't think performance numbers are needed. Differential Revision: https://phab.mercurial-scm.org/D9549

simplemerge: work with opts as native strings instead of bytes There was little reason to use `pycompat.byteskwargs()` in `simplemerge()` as far as I could tell. Differential Revision: https://phab.mercurial-scm.org/D9548

hghave: update the check for virtualenv This started as `hghave --test-features` failing on Windows in `test-hghave.t`. IDK how this worked, as neither my Linux nor Windows machines have the old attribute with virtualenv 20.2.2, even on py2. I think this was noticed recently because 357d8415aa27 mentioned an AttributeError, and mitigated by making this py2 only. But as mentioned, this is also a problem on py2 (where the failure was observed). When I got this working by removing the attribute reference, the command in the test failed because the `--no-site-package` argument was removed some time ago. Therefore, this backs out 357d8415aa27 and references a known good attribute (which was done to suppress the warning about an unused import) that also ensures the command does not need the argument. Since there appears to be (minor) broken stuff on py3, manually apply the `no-py3` guard that was backed out of the check itself. Differential Revision: https://phab.mercurial-scm.org/D9547

singlehead: introduce option to restrict to public changes The new experimental.single-head-per-branch:public-changes-only option restricts the single-head-per-branch filter to public changesets. This is useful when serving one repository with different views as publishing and non-publishing repository. Differential Revision: https://phab.mercurial-scm.org/D9525

treemanifest: stop storing full path for each item in manifest._lazydirs This information is obtainable, if needed, based on the lazydirs key (which is the entry name) and the manifest's `dir()` method. ### Performance This is actually both a memory and a performance improvement, but it's likely to be a very small one in most situations. In the pathological repo I've been using for testing other performance work I've done recently, this reduced the time for a rebase operation (rebasing two commits across a public-phase change that touches a sibling of one of my tracked directories where the common parent is massive (>>10k entries)): #### Before ``` Time (mean ± σ): 4.059 s ± 0.121 s [User: 0.9 ms, System: 0.6 ms] Range (min … max): 3.941 s … 4.352 s 10 runs ``` #### After ``` Time (mean ± σ): 3.707 s ± 0.060 s [User: 0.8 ms, System: 0.8 ms] Range (min … max): 3.648 s … 3.818 s 10 runs ``` Differential Revision: https://phab.mercurial-scm.org/D9553

extensions: avoid including `__index__` in the disabled extension list This generated module contains a dictionary of all bundled extension names and their help for builds that cannot enumerate extensions in the filesystem. The disabled list gets displayed in `hg help extensions`, and is also used by `setup.py` to populate `__index__.py` when building. I haven't seen it sneak into either py2exe or PyOxidizer builds, but it does show up when running tests locally after having created an installer. Differential Revision: https://phab.mercurial-scm.org/D9544